This invention relates to reflective material and more particularly to reflective particles used for reflective marking.
The present invention, while of general application, is particularly well suited for use on highways to provide reflective markers such as edge and lane striping, signs, etc. As is well known, it has become common practice to drop small glass spheres onto a painted line on a highway while the paint is still tacky such that the spheres are partially imbedded in the paint when it has dried. The spheres render the line or other marker retroreflective and reflect the light from headlights so that the marker is more visible to the motorist. In some cases the spheres were imbedded in spherical or irregularly shaped plastic granules prior to being applied to the paint in the manner disclosed in U.S. Pat. Nos. 3,252,376 and 3,254,563, for example, in an effort to further improve the reflectivity of the marker.
Heretofore, difficulties were encountered in the manufacture and use of reflective material of the foregoing type. As an illustration, in many instances the adhesion of the glass spheres to the paint proved deficient, with the result that some of the spheres were loosened by traffic or washed away druing rainstorms, for example, with a corresponding deterioration in the reflectivity of the surface. In addition, the spheres that remained were subjected to severe abrasion under heavy traffic conditions and exhibited flattened upper surfaces which further impaired the reflectivity of the marker. Furthermore, and this has been of special moment during periods of heavy rain, the reflectivity of even freshly applied striping or other marking was deficient in a number of respects.